1. Field of the Invention
The present invention relates to a method of and an apparatus for manufacturing a slide fastener chain with separable bottom end stop members (a first pin member for attaching a box and a second pin member), and a method of producing a slide fastener from the slide fastener chain. More particularly, this invention relates to a method which is capable of continuously manufacturing a plurality of longitudinally spaced slide fastener chains with high accuracy of positioning to cope with the production of slide fasteners of different lengths each having a separable bottom end stop assembly, a method of producing slide fasteners from the slide fastener chains, and an apparatus for carrying out the slide fastener chain manufacturing method.
2. Description of the Prior Art
A molding apparatus disclosed in British Patent No. 1,551,535 includes a mold defining a tape feed passage along which a pair of slide fastener stringer tapes (hereinafter referred to as "fastener tapes") is fed intermittently. In timed relation to the intermittent feeding of the fastener tapes, a molten thermoplastic synthetic material is injected into the mold to form rows of coupling elements molded on and along inner longitudinal confronting edges of the fastener tapes together with end stop members (top end stops). At the same time, to cope with a growing tendency shown toward the multi-product and small-quantity production of slide fasteners, the length of the rows of molded coupling elements can be adjusted.
The mold is composed of a movable mold member and a fixed mold member jointly defining a pair of rows of cavities for forming the coupling elements. Each of the mold members is provided with a slide core in a form of a rectangular block. Each of the slide cores is disposed on a downstream end of the corresponding mold member and slidably movable in a direction perpendicular to the longitudinal axis of a runner. Confronting mold surfaces of the slide cores define two cavities for forming top end stop members, and a depression interconnecting the cavities and the runner. The cavities and the depression are formed in that part of the slide cores which is located on one side of the slide core in the direction of sliding movement of the slide cores. The side surfaces of the slide cores excluding the communicating portion of the depression with the runner form a closing surface to close one opening end of the runner. The slide cores are movable by a cylinder between a first position in which the depression communicates with the runner, and a second position in which the end of the runner is closed. A control bar is slidably inserted from an upstream end of the mold into the runner. By changing the length of insertion of the control bar relative to the runner, the length of rows of molded coupling elements can be adjusted.
To form rows of coupling elements having a desired length which is n times as large as a predetermined length, where n is an integer, the control bar is longitudinally moved to a position where rows of coupling elements of the predetermined length can be molded. Then, a molten thermoplastic synthetic resin material is injected into the mold. Thereafter, the fastener tapes are advanced by a distance equal to the predetermined length of the coupling elements. The foregoing injection-molding process and the tape advancing process are achieved repeatedly by n times provided that in the final injection-molding process, the slide cores are shifted to the first position to communicate the depression with the runner. Subsequently, the fastener tapes are advanced by a distance which is equal to the sum of the predetermined length and the length of an element-free space portion to be provided between two adjacent fastener element chains. By repeating the foregoing sequence of operations, it is possible to continuously manufacture a plurality of longitudinally spaced slide fastener chains each having a pair of rows of coupling elements of the desired length (which is n times of the predetermined length) and top end stop members molded on the fastener tapes. In addition, by properly adjusting the length of insertion of the control bar relative to the runner, a row of longitudinally spaced slide fastener chains each having a pair of rows of coupling elements of a desired length and two top end stop members can be continuously manufactured.
In the manufacture of such a slide fastener chain with a separable bottom end stop assembly, it has been customary to form reinforcing film layers to the fastener tapes to reinforce these portions of the fastener tapes where the members of separable bottom end stop assembly are attached subsequently. Formation of the reinforcing film layers may be achieved by attaching reinforcing films to separable-bottom-end-stop-attaching portions of the fastener tapes before rows of coupling elements are molded on the fastener tapes. However, as disclosed in Japanese Patent Publication No. 63-40085, the reinforcing films are generally attached to the fastener tapes, respectively, adjacent to one end of an element-free space portion defined between two adjacent slide fastener chains each including a pair of rows of coupling elements, for a reason described below.
Since the fastener tapes have a certain degree of stretchability, the length of the fastener tapes is variable with a change in tension on the fastener tapes which may be caused when the fastener tapes are advanced or when rows of coupling elements and members of a separable bottom end stop assembly are attached. Such a change in the length of the fastener tapes is accumulated when the fastener tapes are processed continuously for long hours. Accordingly, if reinforcing film layers are formed on the fastener tapes before rows of coupling elements and members of a separable bottom end stop assembly are molded, an accurate positioning of the reinforcing film layers is not possible due to an accumulated dimensional change of the fastener tapes. Inaccurate positioning of the reinforcing film layers results in inaccurately molded coupling elements and a separable bottom end stop assembly.
In the method of producing a slide fastener chain with end stop members disclosed in the above-mentioned British patent, due to the reason described above, it is not possible to previously form reinforcing film layers on the fastener tapes unless otherwise relying upon any other appropriate measure. Accordingly, the reinforcing film layers should be formed on that portions of the fastener tapes which are located adjacent to the molded end stop members. In this instance, however, since the rows of coupling elements and the end stop members are molded simultaneously, such a reinforcing film attaching method as disclosed in Japanese Patent Publication No. 63-40085 cannot be used without substantial reconstruction. Instead, another reinforcing-film-attaching technique which can be exclusively used in combination with the above-mentioned fastener chain manufacturing method should be developed. To avoid this difficulty, it may be considered that additional to the cavities for molding end stop members, the mold defining the element-forming cavities and the end-stop-members-forming cavities further has cavities for forming reinforcing films, and the end stop members and the reinforcing film layers are molded simultaneously. The thus molded reinforcing films are, however, relatively thick, and a synthetic resin material tends to flow into the material of the fastener tapes, thus making the stringer tapes inflexible. The inflexible fastener tapes having relatively thick reinforcing film layers will cause various problems when subjected to a subsequent processing operation such as sewing operation.